The present invention relates to an actuator adapted to utilize revolution output of a motor such as AC servo motor to perform a predetermined operation, further relates to a motor unit and a controller unit constituting the actuator.
Conventionally, in a mechatronics equipment such as a robot or an NC machine tool, in order to cause each part to perform necessary operation, an actuator, which is adapted to use a motor such as AC servo motor as a drive source, has been used. Recently, as an actuator of this type, an actuator, which includes a motor as the drive source, a drive circuit (driver) for supplying the current to the motor, an operation circuit (controller) for operating current command value (included in control command) to be given to the drive circuit in a common housing; that is, an intelligent actuator has been in practical use. And after assembling the actuator to objective equipment, only by connecting the actuator to an external power supply or an external power supply and an upper controller, predetermined operation can be carried out (refer to, for example, Japanese Patent No. 3332226, Japanese Patent No. 3402597 and Japanese Patent Application Laid-Open No. 5-252688).
In the actuators used for mechatronics equipment as described above, the specifications (rated output, rated torque, rated revolution and the like) required for the motor as the drive source are different depending on the purpose. Therefore, a series of models of motors with various specifications is lined up as drive source, and an appropriate model is selected therefrom in accordance with the purpose.
The above-described intelligent actuators also, which include a driver and a controller along with a motor, have to be organized into a series. In this case, although the control algorithm for operating the control commands is common, controllers having different characteristic parameters used for calculation (rotor inertia, torque constant, torque-revolution characteristic and the like) of the actuator (motor) have to be prepared for each model. Further, it is difficult to cope with the changes in the control algorithm, there resides problems in the aspects of cost effectiveness, reusability and expandability.
To solve the above problems, it is possible to adopt a configuration in which a general-purpose controller externally provided to a motor, which is integrally equipped with a driver, is used. However, in this case, the respective characteristic parameters peculiar to the actuator have to be additionally set up to the employed controller. Not only that satisfactory improvement effect is not obtained, but also there is a possibility of causing an operation failure due to incorrect setting of parameters.